Transmission-circuit.



H. c. EGERTON.

l' TRANSMISSION CIRCUIT. #PFU-camu FILED Aua.ao. 191e.

1,2955'45v4. Patented Feb. 25, f.

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-has therefore been proposed to employ a HENRY c. EGERTON, or Passaic,

enseres NEW JERSEY., ASSIGNOR TO WESQERN ELECTRIC COMPANY, INCORPORATED, OF NEW' YORK, ll'. Y., A CORFORATION OF NEVI YORK TRANSMISSION-CRCUIT- Application filed August 30. ll.

To au 'wiz-0m, t may conccre;

Be it known that l, HENRY C. Eonu'rox, a citizen of the United States, residing at Passaic, in the county of Passaic and State of New Jersey, have invented certain new and useful Improvements in Transmission- Circuits, of which the following is a tull, clear, concise, and exact description -This invention relates to telephone tra-nsmission systems and in particular to a circuit ar 'angement and organization of apparatus for use at a train dispatchers station or -at similar places Where currents ot various intensities are received, and where for any reason the use of the ordinary head or-hancl type of telephonerecei'ver is inconvenient. The object of this invention is to permit the ready reception of messages and the general utilization of the telephone apparatus, with a minimum of manipulation. In certain classes ofteleplione Work and in train despatching by telephone part-icm larIy, the so-called ,loud speaking receiver has assumed considerable importance, in that its use permits the operator to remain in constant touch with the line while attending to other duties and Without the necessity of Wearing rthe heretofore customary head receiver Where an unusually long despatcner's line. is involved or Where for any reason the attenuation of telephonie currents in 'the despatchers line is reat, the incoming currents may be of insuiiizcient strength'to operate a loud speaking telephone effectively, and it repeater or terminal ampliiier betweentlie telephone `line and the loud speaking re ceiver-to increase the power in the receiver to a. sufficient degree for eiiective reception.

will be automatically connected for minimum side tone, when the local transmitting Specification of Letters Patent.

Unless steps are takenlto prerent'it., theA Patented Feb. 235, i919,

serial no. 117,652.

apparatus operated. 'llie invention further provides inaddition to the high power receiving* apparatus which comprises the umpliiicr-receiver combination above mentioned, alow power receirirugA apparatus which may be either a hand or head tele 'phone ot the usual type or a loud speaking receiver used without. an amplifier, which may at will he. inserted in place ofthe. high power apparatus. The invention still further provides that regardless of whether the high power or low power apparatus is momentarily in use, such apparatus will be included in proper circuit relation with respcCt to the transmitting apparatus when the latter is thrown into circuit for transmitting' purpose ln other words, the high. power receiving apparatus ri'ill be included in non-side tone relation, whereas the low power receiving apparatus will not be so includedi The invention will be more clearly understood by reference to the accompanying drawing-s, in which Figure l illustrates the circuit and switching; arrangement of this invention. Fig, represents the condition of this circuit for"transmitting and with the highpower receiving,f apparatus arranged in non-side tone ref Fig. 3 represents ting with the low raro-wer receiving apparatus in circuit. lil sewing condi 'represents the normal jrethe circuit with the high power rece fr apparatus in circuit; and 5 .rean-seu the receiving` arrangement with the low power receiving apparatus in circuit.

Referring to Fig". l, t and 2 are the line coi'icluctors of a train tlespateliing or similar circuit lridgecl across these conductors through one Contact of the switch 3 is an autotranstormer 4. ln parallel with one poitionot' the autotransformer il, through contacts 5, t or' the ltey 'l' is the receiving element or input circuit of a telephone amplifier 8, here shown in conventional form, it being understood thatiany suitable type of telephone may be used. The output circuit of the repeater 8 is connected through. th' transformer 9 to a loud speaking receiver l0. ln this, the normal arrangetill power receiving apparatus, comprising the repeater 8 and the loud speaking receiver 10, is associated directly with the line conductors through the medium of the autotransformer 4f, Whose function itis to accomv fortably largevoluine of sound, in which caseA the switch 3 may be operated closing contact with point, 1land. bringing the loud simplied form in Fig. 5.v In this lower power receiving circuit, there .may be' included instead' of the loud speaking receiver 12, a hand or a head receiver 13, which,y

y upon its removal from the switchhook 14, is

placed in circuit' across Athe line, a short circuit being established across the receiver 12. On the return of the receiver 13 to the svvitchhook 14, the short circuit is removed from receiver 12 and ashort circuit established f'or the receiver 13. -Receiver 18 is,

of occasional use in case secrecy of com-A munication 1s desired 'or if for any, reason the noise conditions in the despatcliers oiiice' make thev use ci a loud speaking telephone` difficult...

In transmitting from the station, herein. shown, the key 7 is depressed, thusclosing,

the contacts 6,-15 and 1617j-18.' The operation of -this key' by closing. contacts 16-17J-18 completes thefcircuit across the line conductors through the secondaries 19 and 20 of the induction coil 21 iii-series with the artificial line.22 which is'designed to sii'nulatel the impedance of the despatchers line. At the same time the closure of contact 16,-17 completes the primary circuit of the induction. coil 21, including ythe trans'l niitter 23`and the primary Windingl 2 4 and battery 25. The opening of the" contacts 5--6 removes the re eater 8 fromconnection with the auto-trans ormer 4 and connects it to the junction of the secondary'windings'A 19 and 20.

In this condition the amount ofthe local currents generated by the transmitter 23 which will flow through the repeater 8, will depend upon. the degree to which the arti` fic-'ral line 22is a Vtrue copy of the real lined speaking receiver 12 into"'ci1cuit,across' theA 15 l l comprisingtransmitting necesariak `The lcircuit arrangement just described is shown in simplified form in Fig. 2. Vllien .the switch 3 is thrown 'into contact'with point 1l, the circuit condition Will be as illustrated in simplified form in F 3. In vthis condition, it will be noted that the 10W ower receiver 12 is bridoed .directl across 75 tlieline conductors 1 and 2in parallel With the secondaryV circu-it of the induction coil 21. lThis'arrangement is desirable inasmuch. as, Aif the receiver 12 Were included in lthe nonn side tone relation With respect tothe induc- This circuit arrangement is'illustrated in tion coil 21, the volume of side tone would be insufficient to enable the operator to de.-

termine Whether his transmitter apparatus Was Workingproperly or not.

f The -circuit arrangement herein described l the particular receiving device then in circuit shall be associated with the transmitting,

induction coil in" the lmost suitable side tone relation.

VVh'at -is claimed is:

41. In a transmission system, the combination with line conductors of a local station and receivingl means, means intermediate said line con-v ductors and said receiving means for amplifying the received currents, artificial line 100 means for rendering said amplifying means insensitive to currents transmitted from.

.said local station, and vmeans for operatively controlling said artificial line.

2.111 a transmission system, va pair of line conductors, an ampliiier, a. bridge across said line conductors normally including said amplifier, a transmitting induction coil, and swtching means for removing said amplifier from said bridge and placing it in non-side tone relation with respect to said induction'coil. i i

3. In 'a transmission system, a pair of line conductors, an amplifier, a bridge across said line conductors normally including said `11a amplifier, a ltransiiiitting induction coil having a primary circuit and a secondary circuit, and switching means for simultaneously removing said amplifier from said bridge, closing said primary circuit, bringing said amplifier into non-side tone relation with respect to said secondary circuitand bridging said secondary circuit across said line conductors.

4. In a transmission system, a pair of line conductors, a transmitting induction coil, switching means for placing said induction coil in circuit with said line conductors, a high power receivingr means and a low power receiving means, and means for at will placing either said low power receiving means in shunt of said induction'coil or said high` power receiving means in non-side tone relation thereto. Y

In a transmission system, the combination'with line conductors, of a local station comprising an induction coil having a primary winding and two secondary windings, a transmit-ter in circuit with said primary Winding, a bridge across' said line including said secondary windings and lanartiicial line in series, an 'amplifier having an input circuit and an output circuit, switching means for simultaneously closing said primary circuit and said bridge circuit and for connecting said input circuitl across one of said secondary4 windings and said artificial line, and a-loud speaking receiver connected to said output circuit.

-mally in circuit with said 6. In a transmission circuit, the combination with a pair of line conductors, of a local station comprising an induction coil having a primary Winding and two secondary Windings, an .artificial -line in series withsaid secondary Winding, a bridge across said line, a high power receiving means nor- A bridge, and a switching means for simultaneously closing said primary circuit, connecting -said secondary windings and said artificial line in series across said line conductors, said receiving means from said bridgeand connecting it in shunt of one of said secondary windings and said artiiicial line.

In witness wher f, Ihereunto subscribe my name this. 29th dayng'if August, A. D., 1916. l

HENRY C. EGERTON.

alsl

so removing 

